An image of a chair with wheels is inscribed into a sarcophagus in China, with the date of the inscription estimated to be around the sixth century, A.D. Wheelchairs did not become common, however, until the late 19th century.
U.S. Pat. No. 531,330 to Sarah A. Potter (“the Potter patent”) shows an example of an early patent for the modern wheelchair. The wheelchair provides a seat back, seat bottom, and footrest. An occupant may rest in the wheelchair in a sitting position. The seat back, seat bottom and footrest are part of a mechanical frame for the wheelchair. Also attached to the frame are two sets of wheels, one smaller set in front (“the front wheels”), and one larger set in the rear, mounted to a rear axle (“the drive wheels”). Attached to the outer rim of the drive wheels is a grip, with which an occupant of the wheelchair may manually rotate the drive wheels and move the chair. The wheelchair shown in the Potter patent also allows for the seat back to be lowered and the footrest to be raised so that the occupant may rest in a reclining position. The modern wheelchair, as shown by way of example in the Potter patent, is simple and useful, allowing an occupant to manually move around while in a sitting position.
One disadvantage to the design of the wheelchair shown in the Potter patent is that the occupant of the wheelchair is confined to the sitting (or reclining) position. For some wheelchair occupants, for example, double amputees, this does not represent a disadvantage. But for many wheelchair users, such as paraplegics, it is desirable for the wheelchair to allow its occupant to be in either a sitting position or a standing position. Among the many desirable advantages of a wheelchair that allows for its occupant to be in a standing position, there are the ability to use conventional counter tops and common appliances designed for use in a standing position, and the ability to reach items high up in a kitchen cabinet or on a grocery store shelf. There are also physiological advantages to allowing the occupant to be in a standing position. Standing can help reduce the risk of developing osteoporosis, tone the cardiovascular system, reduce muscle spasticity, prevent contractures, improve renal function, and relieve pressure from sensitive areas, preventing pressure sores. Finally, and perhaps most importantly, a wheelchair that allows for its occupant to be in a standing position can be of great psychological advantage. It affords its occupant an escape from being literally looked down upon. From a standing position, the occupant may look at other people eye to eye instead.
Attempts have been made to develop a standing wheelchair. U.S. Pat. No. 3,640,566 to Hodge (“the Hodge patent”) shows a spring loaded wheelchair that assists a disabled person in moving from a sitting position to a standing position. The wheelchair of the Hodge patent cannot, however, be moved around while an occupant is in the standing position. The foot rest 22 shown in FIGS. 1–6 of the Hodge patent lowers to the ground when the wheelchair shifts from a sitting position to a standing position, preventing the chair from being moved at all while in the standing position.
U.S. Pat. No. 4,569,556 to Bernard Pillot (“the Pillot patent”) teaches a wheelchair that allows for an occupant to be raised from a sitting to a near standing position (called the “pseudo-vertical position” in the Pillot patent) by “an articulated structure” of two “deformable quadrilaterals” and an “elastic member”, which appears from the drawings to be a gas spring, or some other kind of hydraulic device. The wheelchair of the Pillot patent allows for an occupant to be moved in the standing position (as the wheelchair of the Hodge patent does not), but it does not allow an occupant to move around under his or her own power, i.e., the wheelchair of the Pillot patent cannot be moved by the occupant while the occupant is in the standing position. Thus, without the help of another, the wheelchair of the Pillot patent does not grant an occupant more mobility than the wheelchair of the Hodge patent. Furthermore, as in the Hodge patent, the wheelchair of the Pillot patent does not allow the occupant to lift himself or herself into the standing position. The energy for moving from the sitting position to the standing position is provided by the “elastic member”, labeled 38 in FIGS. 1–3. Should the “elastic member” break or malfunction, the occupant would be forced to remain in the sitting position.
The wheelchairs of the Hodge patent and the Pillot patent have been further developed by other inventors in various ways. For examples of wheelchairs similar to that of the Hodge patent, see U.S. Pat. Nos. 4,231,614 and 4,598,944, which show wheelchairs that allow an occupant to move to a standing position, and remain stationary in the standing position. For examples of wheelchairs similar to that of the Pillot patent, see U.S. Pat. Nos. 5,609,348 and 5,772,226, which show wheelchairs that assist an occupant in moving from a sitting position to a standing position with a hydraulic device. The invention of U.S. Pat. No. 5,772,226 allows an occupant to move while in the standing position with the assistance of a electricity source (labeled “12” in FIG. 1) and a motor (labeled “11” in FIG. 1).
A need exists for a manually operable wheelchair that allows for an occupant to move himself or herself from a sitting position to a standing position, and to move around manually while in the standing position.